Technique for providing programming content through a communications network having limited bandwidth

ABSTRACT

In a cable television system, a specific carrier is assigned to deliver programming content of a program channel to a service area for a period, defined as a function of viewership of the program channel during that period. For example, the program channel is assigned the specific carrier during the time when it has a generally strong viewership. Otherwise, the program channel is assigned a carrier on an as needed basis, i.e., only when one or more subscribers in the service area request such a program channel. Viewing statistics are generated to identify viewership patterns or viewing habits of the subscribers in the service area with respect to a given program channel. In another embodiment, based on the viewing statistics, popular and unpopular programs, program elements, program lineups, program channels are identified on a temporal and/or regional basis.

PRIORITY

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/429,998 filed on May 5, 2003 of the same title,and issuing as U.S. Pat. No. 8,910,221 on Dec. 9, 2014 which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to a communications system and method, and moreparticularly to a community access television (CATV) system and methodfor providing program material through a cable network having limitedbandwidth.

BACKGROUND OF THE INVENTION

Cable television is typically provided by delivering televisionprogramming through a community access television (CATV) system tosubscribers. Specifically, in delivering the television programming, aheadend in the CATV system distributes program data streams containingprogram materials through different channels of a distribution network,which occupy specified frequency bands. The program data stream for eachchannel is used to modulate a carrier associated with the channel, Theresulting modulated carriers are combined and transmitted through thedistribution network to a service area node, where the combinedmodulated carries are provided to a service area. A subscriber in theservice area utilizes a set-top terminal to receive the combinedmodulated carriers and tune to a desired channel to obtain the programmaterial from the associated modulated carrier.

In prior art, the combined modulated carriers provided to a service areacontain program materials of all channels used in a CATV system.However, as a cable TV provider uses an increasing number of channels todeliver additional program materials to attain a larger subscription,the number of available channels will soon run out. Thus, an urgent needarises where an efficient utilization of the limited bandwidth of thedistribution network is required to deliver the additional programmaterials.

SUMMARY OF THE INVENTION

A copending, commonly assigned U.S. application Ser. No. 09/956,688(“the '688 application”) filed on Sep. 20, 2001 discloses a switchedbroadcast technique for redressing some of the prior art deficiencies.According to such a technique, selected program channels are madeavailable to subscribers in the same service area on an as needed basis.As a result, the number of program channels furnished, although notsimultaneously, by a system using the switched broadcast technique mayexceed the maximum number of carriers allowed.

The present invention improves the switched broadcast technique byidentifying “popular” program channels, which command generally strongviewership in a service area. In accordance with the invention, apopular program channel may be assigned a carrier on a long term basis,not subject to reassignment according to the switched broadcasttechnique as soon as no set-top terminals in the same service area aretuned to such a program channel. The invention, in part, is based upon arecognition that even though a program channel is popular, there may bebrief moments in which all set-top terminals in the same service areaare tuned away from such a program channel. Thus, the invention improvesthe switched broadcast technique by assigning a carrier to a popularprogram channel for a period despite intermittent viewership, therebyadvantageously saving the system resources otherwise needed tofrequently assigning and reassigning a carrier therefor during such aperiod.

In an illustrative embodiment, the popularity of a program channel isdetermined based on viewing statistics, which are generated based ondata in requests issued from the set-top terminals in a service area.The requests may be issued in response to the subscribers at the set-topterminals selecting and deselecting the program channel. Based on theviewing statistics, at least one period in which the program channel isin a particular status (e.g., being popular) is identified. For example,a program channel is considered popular when the number of set-topterminals receiving programming content associated with the programchannel exceeds a threshold. A selected carrier is assigned to deliverthe programming content associated with the program channel for theidentified period.

The invention is also based upon a recognition that popularity of aprogram channel may change by day or even time of day. Thus, inaccordance with an aspect of the invention, a popular program channelmay be assigned a particular carrier until the program channel becomes“unpopular.” At such time, the particular carrier may be assigned toanother popular program channel, and the unpopular program channel isthen subject to switched broadcast. Further, a carrier may be shared bycomplementary program channels, where one program channel is popular fortimes when the other program channel is unpopular, and vice versa.

Thus, in a second embodiment of the invention, viewing statistics aregenerated based on data in requests concerning at least first and secondprogram channels, which are issued from the set-top terminals in aservice area. Based on the statistics, a first period and a secondperiod in which the first program channel and the second program channelare in a certain status are determined, respectively. The first andsecond periods are non-overlapping. A carrier is allocated to deliverprogram material associated with the first program channel to theservice area for the first period. The same carrier is re-allocated todeliver program material associated with the second program channel tothe service area for the second period. The carrier may be repeatedlyallocated and re-allocated in a similar manner.

In addition, the viewing statistics may be used to identify popular orunpopular program elements including, e.g., TV shows; commercials;skits, monologues and chapters made part of TV shows; etc. The programelements associated with a program channel are provided in a sequence toa service area according to a predetermined schedule. Based on theviewing statistics, a period in which the program channel is in aparticular status (being popular or unpopular) is determined. A subsetof the popular or unpopular program elements provided in the period isidentified based on the predetermined schedule. Further, by aggregatingthe viewing statistics concerning multiple service areas which comprisea region, e.g., the South, Midwest, Northeast, West Coast, etc.,regional acceptance of a program element may be determined.

In a third aspect, an apparatus configured to controllably deliverprogramming content associated with a program source in response torequests from a plurality of terminals in a service area is disclosed.In one embodiment, the apparatus comprises: an interface configured toreceive the requests, a memory configured to store a first set ofstatistics generated based on data obtained from first ones of therequests received during a first time interval, and a processingelement. The processing element is configured to: (i) identify, based onthe first set of statistics, that the program source has previouslyattained a threshold level of demand in the service area at anidentified period of time within the first time interval; (ii) based onthe identification, assign a selected carrier to deliver the programmingcontent associated with the program source to the service area duringthe identified period of time, the carrier not reassigned to a differentprogram source when there are no user requests for the programmingcontent nor users currently tuned to the programming content; and (iii)deliver the programming content associated with the program source tothe service area according to switched digital broadcast mechanisms attimes other than the identified period of time.

In a fourth aspect a method for controllably delivering a firstprogramming content associated with a first program source and secondprogramming content associated with a second program source in responseto requests from a plurality of terminals in a service area isdisclosed. In one embodiment, the method comprises: (i) storing a set ofstatistics based on data obtained from requests received for programcontent, the requests comprising requests for the first programmingcontent from the first program source and requests for the secondprogramming content from the second program source received during afirst time interval; (ii) identifying, based at least in part on the setof statistics, a first plurality of future time periods in which thefirst program source will attain a threshold level of demand in theservice area and a complementary plurality of future time periods inwhich the second program source will attain the threshold level ofdemand in the service area, the first plurality of future time periodsand the complementary plurality of future time periods being mutuallyexclusive time periods; (iii) assigning, based on the identification, aselected carrier to deliver the first programming content associatedwith the first program source to the service area during the firstplurality of future time; (iv) during periods other than the firstplurality of future time periods, causing the first programming contentassociated with the first program source to be delivered to the servicearea according to switched digital broadcast mechanisms; (v) assigning,based on the identification, the selected carrier to deliver the secondprogramming content associated with the second program source to theservice area during the complementary plurality of future time periods;and (vi) during periods other than the complementary plurality of futuretime periods, causing the second programming content associated with thesecond program source to be delivered to the service area according toswitched digital broadcast mechanisms.

In a fifth aspect, a non-transitory computer readable apparatuscomprising a plurality of instructions which are configured to, whenexecuted by a processor controllably deliver programming contentassociated with a program source in response to requests from aplurality of terminals in a service area is disclosed. in oneembodiment, is accomplished via: (i) collection of tuning datacomprising a plurality of records associated with a plurality of programchannels in a switched digital network, each of the plurality of recordscomprising a timestamp of a channel change request, a channel identifierassociated with a first programming channel, and a service areaidentifier of a particular service area; (ii) based on the collection ofthe plurality of records, determination of a number of subscribers inthe particular service area which are currently tuned to the firstprogramming channel; (iii) generation of a set of service area specificstatistics based on the collection of the tuning data, the set ofservice area specific statistics comprising viewership at different timeintervals; (iv) identification, based at least in part on the set ofservice area specific statistics, of a plurality of time periods inwhich the program source is predicted to attain at least a thresholdlevel of demand; and (v) assignment of a selected carrier to deliver theprogramming content associated with the program source to the servicearea during the identified periods based at least in part on the set ofservice area specific statistics, the carrier not being reassigned to adifferent program source when there is a lack of user requests for theprogramming content existing during the identified periods; (vi) duringperiods other than the identified future periods, delivery of theprogramming content associated with the program source to the servicearea according to switched digital broadcast mechanisms.

BRIEF DESCRIPTION OF THE DRAWING

Further objects, features and advantages of the invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawing, in which:

FIG. 1 is a block diagram of a hybrid fiber coax cable CATV system inaccordance with a switched broadcast technique;

FIG. 2 illustrates selected carriers for transmitting program materialsand control messages in a forward passband of the system of FIG. 1;

FIG. 3 is a block diagram of a controller used in the system of FIG. 1;

FIG. 4 is a table used by the controller for dynamically assigning thecarriers for transmission of program materials in accordance with theswitched broadcast technique;

FIG. 5 illustrates a data format of a request processed by thecontroller;

FIG. 6 is a flow chart illustrating a process for processing therequest;

FIG. 7 is a flow chart illustrating a process for retiring an unusedcarrier;

FIG. 8 is a block diagram of a data analyzer/controller used in thesystem of FIG. 1, in accordance with an inventive, improved switchedbroadcast technique;

FIG. 9 tabulates certain data collected from requests processed by thedata analyzer/controller; and

FIG. 10 tabulates viewing statistics generated by the dataanalyzer/controller based on the collected data.

DETAILED DESCRIPTION

The invention is an improvement on a switched broadcast techniquedisclosed, e.g., in copending, commonly assigned U.S. application Ser.No. 09/956,688 (“the '688 application”) filed on Sep. 20, 2001, which isincorporated herein by reference. In accordance with the switchedbroadcast technique, a communications system, e.g., a CATV system, makesavailable to subscribers in the same service area selected programchannels on an as needed basis. In order to fully appreciate theinvention, one needs to learn about the switched broadcast technique, animplementation of which will now be described.

Switched Broadcast Technique

FIG. 1 illustrates hybrid fiber coax (HFC) cable CATV system 10incorporating the switched broadcast technique for providing programmaterials to set-top terminals on the subscriber premises. As shown inFIG. 1, system 10 includes headend 100, fiber node 122, cabledistribution network 124, and service area nodes, e.g., node 126 whichis connected to set-top terminals 128-1 through 128-L in a service area,where L is a predetermined number.

In headend 100, program material processing unit 102 receives programmaterials from various sources via satellites, terrestrial microwavetransmissions, cable, etc. The program materials are processed by unit102 to form K individual program data streams in a digital format, whereK is an integer. Each program data stream contains program material,which requires a transmission channel having a specified frequency bandfor its distribution. It should be noted that the term “transmissionchannel” used here should not be confused with a “program channel.” A“transmission channel” signifies a designated frequency band throughwhich a program data stream containing program material is transmitted.On the other hand, a “program channel” signifies the source of theprogram material selected by a subscriber to view. For example, asubscriber may select program channel 2 to view program materialprovided by CBS, program channel 14 to view program material provided byESPN; program channel 32 to view program material provided by MTV, etc.In this instance, there are K program channels corresponding to the Kprogram data streams.

Under control of controller 112, switching unit 104 selects and switchesa subset of the K program data streams, say, p program data streams tomodulator bank 106, where p≦K. The program data streams in the subsetare selected in a manner described below. Each selected program datastream is transmitted through a different transmission channel after itmodulates a carrier associated with the transmission channel in adesignated forward passband. As is well known, in the United States thedesignated forward passband for cable TV ranges from 50 MHz to 550 MHz.However, it will be appreciated that a person skilled in the art mayutilize other forward passbands, instead.

FIG. 2 illustrates M carriers, C₁ through C_(M), associated with Mtransmission channels in the forward passband, respectively, which arepre-selected for use in this instance. Since the forward passband islimited in bandwidth, M in this instance represents the maximum numberof carriers or transmission channels that the forward passband canaccommodate. As shown in FIG. 2, the carrier frequency of C₁ is denotedCF₁; the carrier frequency of C₂ is denoted CF₂; . . . ; and the carrierfrequency of C_(M) is denoted CF_(M). In addition, a control carrier CChaving a carrier frequency CCF is assigned to carry control messages bycontroller 112 to the set-top terminals through a control channel in theforward passband.

In accordance with the switched broadcast technique, carriers aredynamically assigned to carry program materials of only those programchannels selected by the set-top terminals (or subscribers) in a servicearea. The number of program channels that the CATV system can provide,although not simultaneously, can exceed M. That is, K can be greaterthan M in this instance.

Controller 112 communicates to switching unit 104 through link 116,causing unit 104 to switch, to modulator bank 106, the selected pprogram data streams which contain the program channel materialsselected aggregately by the subscribers in the service area. As long asp≦M, controller 112 manages to assign p carriers to carry the respectivedata streams. To that end, controller 112 also specifies to unit 104 theselected inputs of modulator bank 106 to which the p data streams areswitched.

In this instance, modulator bank 106 includes conventional modulators.Each input to modulator bank 106 is fed to a different modulator formodulating the input onto one of the M carriers. The p data streams areswitched by unit 104 to the appropriate inputs of modulator bank 106 tobe modulated onto the p assigned carriers, resulting in p data signalsrepresenting the modulated carriers, respectively. In addition,controller 112 transmits control messages described below, through link114, to modulator bank 106 where a modulator modulates the controlmessages onto the aforementioned control carrier, resulting in a controlsignal representing the modulated control carrier.

Combiner 108 combines the p data signals and control signal to form acombined signal, which is fed to optical transceiver 110. The lattergenerates an optical signal representing the combined signal. Theoptical signal traverses optical fiber 113 to fiber node 122. Atransceiver (not shown) in fiber node 122 which performs the inversefunction to transceiver 110 converts the optical signal back to thecombined signal in electrical form. The combined signal traverses cabledistribution network 124 to, say, service area node 126, where thecombined signal is multicast to set-top terminals 128-1 through 128-L. Aset-top terminal may be tuned to the control carrier frequency CCF andextract the control signal from the received combined signal. Thecontrol signal may contain information identifying the carrier which isassigned to carry the program channel material selected by the set-topterminal. Based on any such information, the set-top terminal is tunedto the frequency of the identified carrier and extracts thecorresponding data signal from the received combined signal. Theselected program channel material is then derived in a well known mannerfrom the extracted data signal for viewing.

Referring to FIG. 3, controller 112 includes processor 204 ofconventional design, which is connected to memory 206 and interface 202.Processor 204 receives, e.g., from one or more of set-top terminals128-1 through 128-L, requests for materials of program channels selectedthereby. Such requests are processed by processor 204 in accordance withroutines stored in memory 206 which are described below. It suffices toknow for now that in response to one such request, processor 204 causesswitching unit 104 to switch the program data stream corresponding tothe requested program channel to a selected input of modulator bank 106and assigns an unused carrier for transmitting the data stream ifprocessor 204 has not done so. In addition, processor 204 transmits acontrol message receivable by the requesting set-top terminal, whichincludes the information identifying the carrier assigned by processor204 to carry the requested program channel material. As mentionedbefore, based on such information, the requesting set-top terminal istuned to the frequency of the identified carrier to obtain the selectedprogram channel material.

To manage the dynamic assignment of carriers for transmitting requestedprogram channel materials to each service area, an assignment table isused in this instance which is stored in memory 206. FIG. 4 illustratessuch an assignment table (denoted 300), which includes columns 304, 306and 308. Column 304 enumerates each program channel X selectable by asubscriber through a set-top terminal, which ranges from 1 to K in thisinstance. Column 306 tracks, for each program channel X, the number ofsubscribers in the service area selected that program channel to watch(N_(PCHX)). Column 308 includes entries identifying the carriersassigned by processor 204 to carry the respective materials of programchannels X. Thus, with assignment table 300, processor 204 has knowledgethat, for example, referring to row 311, carrier C₃ (one of the carriersC₁ through C_(M)) is assigned for program channel 2 (X=2) which 12subscribers (N_(PCHX)=12) have selected to watch. In addition, asindicated in row 313, no subscriber (N_(PCHX)=0) has selected to watchprogram channel 1 (X=1). As such, no carrier (Null) is assigned forprogram channel 1. That is, program channel 1 material is currently nottransmitted to service area node 126 and thus not currently madeavailable in the service area.

When a subscriber at a set-top terminal selects a different programchannel to watch, a request for material of the newly-selected programchannel is sent from the set-top terminal to controller 112. It shouldbe noted at this point that each of set-top terminals 128-1 through128-L is pre-assigned with an identifier for identifying the set-topterminal. FIG. 5 illustrates the request which includes, among others,STID field 402 containing an identifier identifying the requestingset-top terminal, PCH_(NEW) field 404 containing the newly-selectedprogram channel number, PCH_(OLD) field 406 containing thepreviously-selected program channel number, TIME field 407 containing atime stamp of the request, and service group identification (SGID) field408 containing an identifier identifying the service group to which theset-top terminal belongs. In this instance, terminals 128-1 through128-L are in the same service area having the same SGID value, which areserved by common modulator facility.

Thus, for example, if the subscriber changes the program channelselection from channel 8 to channel 2 (or in other words “deselects”channel 8 in favor of channel 2), the value of PCH_(NEW) field 404 wouldbe set to “8” and that of PCH_(OLD) field 406 would be set to “2.” Ifthe subscriber has just turned on the cable TV to watch program channel9, the value of PCH_(NEW) field 404 in that instance would be set to “9”and that of PCH_(OLD) field 406 would be set to “0,” indicating an offstate. Conversely, if the subscriber who has been watching programchannel 9 chooses to turn off the cable TV, the value of PCH_(NEW) field404 would be set to “0” and that of PCH_(OLD) field 406 would be set to“9.”

Referring back to FIG. 1, the above-described request is generated bythe requesting set-top terminal, say, terminal 128-1, which incorporatesa cable modem for modulating a specified carrier in a reverse passbandwith the request data. As is well known, in the United States thereverse passband, which ranges from 5 MHz to 42 MHz, is allocated fortransmission of signals from set-top terminals to a headend to realizeinteractive services, e.g., the present cable TV service. However, itwill be appreciated that a person skilled in the art may utilize otherreverse passbands, instead. The modulated signal from terminal 128-1representing the request data is fed to service area node 126, fromwhere it is forwarded to fiber node 122 through cable distributionnetwork 124. In fiber node 122, the aforementioned optical transceiver(not shown) generates an optical signal representing the modulatedsignal. The optical signal traverses optical fiber 115 to opticaltransceiver 110 in headend 100. Optical transceiver 110 converts theoptical signal back to the modulated signal in electrical form. Themodulated signal is then demodulated by demodulator 130 to recover theoriginal request, which is fed to controller 112 through link 118. Inresponse to the received request, controller 112 invokes a first routinestored in memory 206.

Instructed by the first routine, processor 204 reads the receivedrequest, as indicated at step 502 in FIG. 6. At step 504, processor 204determines whether PCH_(NEW) field 404 in the request has a nonzerovalue f, 1≦f≦K. If not, i.e., the PCH_(NEW) field value equal to “0”indicating that the subscriber's cable TV has been turned off, theroutine comes to an end. Otherwise, processor 204 at step 506 looks up,in assignment table 300, the value of N_(PCHX) with X=f in this case. Atstep 508, processor 204 determines whether the N_(PCHX) value lustlooked up equals 0. If N_(PCHX)=0, analogous to the previously describedsituation with respect to row 313 of table 300, no carrier has beenassigned to carry the requested program channel material to service areanode 126. That is, the requested program material is currently not madeavailable to the service area. In that case, processor 204 at step 510assigns an unused carrier to carry the requested material of programchannel X=f. The new carrier may be selected to avoid as much aspossible noise and interference with other carriers being used tooptimize the cable TV quality. At step 512, processor 204 updatesassignment table 300 to include the identity of the carrier assigned forprogram channel X=f. Processor 204 at step 516 communicates to switchingunit 104, directing it to switch the program data stream associated withprogram channel X=f to the proper input of modulator bank 106 such thatthe program channel material is modulated onto the newly-assignedcarrier directed to the service area identified by the SGID from therequest. At step 518, processor 204 generates a control messageresponsive to the received request, which is to be read by therequesting set-top terminal, terminal 128-1 in this instance. Thecontrol message includes, among other information, the STID from therequest identifying terminal 128-1 which is the intended recipient ofthe message, and the identity of the assigned carrier carrying therequested program channel material. The control message is transmittedthrough the control channel in a manner described before and multicastfrom service area node 126 to the set-top terminals in the service area.In particular, terminal 128-1 is tuned to the control channel and readsthe STID information in the control message, which identifies terminal128-1 in this instance. Recognizing that it is the intended recipient ofthe message, terminal 128-1 goes on to read other information in themessage including the identity of the assigned carrier carrying itsselected program channel material. With the knowledge of the assignedcarrier's identity, terminal 128-1 is tuned to the frequency of theassigned carrier to receive the selected program channel material.

In any event, the routine proceeds from step 518 to step 520 whereprocessor 204 increments the value of N_(PCHX) with X=f in assignmenttable 300 by one, reflecting the fact that an additional subscriber (orset-top terminal) in the service area has selected program channel X=fto view. Referring back to step 508, if processor 204 determines thatthe value of N_(PCHX) with X=f does not equal 0, i.e., at least one settop terminal currently receiving program channel X material carried by apreviously assigned carrier, the routine proceeds to step 514. Processor204 at step 514 looks up, in assignment table 300, the identity of thecarrier previously assigned for program channel X=f. The routine thenproceeds to step 518 described before.

After the first routine is completed, a second routine is invoked toperform a garbage collection function for retiring any carrier carryingprogram material which is no longer selected by any set-top terminal inthe service area. Instructed by this second routine, processor 204 atstep 604 determines whether PCH_(OLD) field 406 in the received requesthas a nonzero value g, 1≦g≦K. if not, i.e., the PCH_(OLD) field valueequal to “0” indicating that the subscriber's cable TV has just beenturned on, the second routine comes to an end. Otherwise, processor 204at step 606 looks up, in assignment table 300, the value of N_(PCHX)with X=g in this case. At step 608, processor 204 decrements theN_(PCHX) value just looked up by one, reflecting the fact that one fewersubscriber (or set-top terminal) in the service area selected programchannel X=g to view. Processor 204 at step 610 determines whether theresulting N_(PCHX) value equals 0. if not, the second routine comes toan end. Otherwise, if N_(PCHX)=0, i.e., program channel X=g no longerselected by any subscriber (or set-top terminal) in the service area,the second routine proceeds to step 612. Processor 204 at step 612searches assignment table 300 for the identity of the carrier assignedfor program channel X=g. Processor 204 at step 614 communicates toswitching unit 104, causing unit 104 to stop switching the program datastream corresponding to program channel X=g to modulator bank 106,thereby terminating the transmission of the program data streamotherwise carried by the identified carrier. Processor 204 at step 616places the identified carrier in reserve by substituting the carrieridentity entry with “Null” in assignment table 300.

Improved Switched Broadcast (ISB) Technique in Accordance with theInvention

The invention improves the switched broadcast technique, describedabove, by not subjecting each program channel to switched broadcastindiscriminately. For example, in accordance with the inventive ISBtechnique, a “popular” program channel commanding generally strongviewership in a service area may be assigned a carrier on a long termbasis, not subject to reassignment according to the switched broadcasttechnique as soon as no set-top terminals in the same service area aretuned to such a program channel. The invention, in part, is based upon arecognition that even though a program channel is popular, there may bebrief moments in which all set-top terminals in the same service areaare tuned away from such a program channel. Thus, the invention improvesthe switched broadcast technique by assigning a carrier to a popularprogram channel for a period despite intermittent viewership, therebyadvantageously saving the system resources otherwise needed tofrequently assigning and reassigning a carrier therefor during such aperiod.

The invention is also based upon a recognition that popularity of aprogram channel may change by day or even time of day. Thus, inaccordance with an aspect of the invention, a popular program channelmay be assigned a particular carrier until the program channel becomes“unpopular.” At such time, the particular carrier may be assigned toanother popular program channel, and the unpopular program channel isthen subject to switched broadcast. Further, a carrier may be shared bycomplementary program channels, where one program channel is popular fortimes when the other program channel is unpopular, and vice versa. Forexample, a cartoon channel, sports channel, talk show channel and moviechannel may be complementary in that a cartoon channel is popular onweekend mornings, sports channel on weekend afternoons, talk showchannel on weekday daytimes and movie channel on both weekday andweekend night times. Thus, in accordance with the invention, a carriermay be cycled through such complementary program channels such that thecarrier is assigned to the cartoon channel for weekend mornings, to thesports channel for weekend afternoons, to the talk show channel forweekday daytimes and to a movie channel each night. While one of thecomplementary program channels is assigned the carrier, the otherprogram channels are subject to switched broadcast.

In an illustrative embodiment, the determination of popularity of aprogram channel is conducted by data analyzer/controller (DA/C) 812 inFIG. 8, which replaces controller 112 in system 10. Similar tocontroller 112, DA/C 812 includes interface 802, processor 804 andmemory 806. However, DA/C 812 in this instance not only performs all ofthe functions of controller 112 described above, but also collects andanalyzes data to determine popular program channels and periods in whichthey are popular, and assigns carriers to the popular program channelson a permanent basis for such periods. To that end, processor 804 inDA/C 812 collects additional data from requests of FIG. 5, concerningselection and deselection program channels which are subject to switchedbroadcast. As described before, such requests originate from the set-topterminals to which DA/C 812 corresponds.

FIG. 9 illustrates the collected data in memory 806 in table form,denoted 900. Column 902 of table 900 enumerates the time stamps in field407 of the requests received by DA/C 812. Column 904 enumerates thecorresponding program channels X selected or deselected in the requests,as indicated in field 404 thereof. Column 905 enumerates thecorresponding SGIDs in field 408, indicating the service areas fromwhich the requests come. Like column 306 described before, column 906tracks, each time after a request concerning program channel X isprocessed, the number of set-top terminals (N_(PCHX)) in the servicearea which are turned to channel X.

Based on the collected data, processor 804 may generate variousstatistics concerning different program channels and their viewershipfor different time frames, e.g., different times of day, days of week,seasons of year, etc., to determine popularity of the program channelsand useful trends on a temporal basis. In addition, processor 804 maygenerate various statistics concerning different program channels andtheir viewership for different service areas which may comprise ageographic region, e.g., the South, Midwest, Northeast, West Coast, etc.to determine popularity of the program channels and useful trends on aregional basis. Without loss of generality, FIG. 10 illustrates a table(denoted 1000) containing viewing statistics concerning a given weekdayfor a given service area, which are extracted from the collected data,e.g., table 900, at specified time intervals, e.g., 10 minutes. As shownin table 1000, each column is associated with a different programchannel. For example, column 1003 is associated with program channel 50,which in this instance represents a talk show channel. Column 1005 isassociated with program channel 51, which in this instance represents amovie channel. Column 1007 is associated with program channel 52, whichin this instance represents a cartoon channel. Column 1009 is associatedwith program channel 53, which in this instance represents a sportschannel. Column 1011 is associated with program channel 54, which inthis instance represents a music video channel. Each entry in a columnrepresents the number of set-top terminals tuned to the program channelassociated with the column at a specified time. For example, entry 1021in column 1011 indicates that 63 set-top terminals in the given servicearea are tuned to program channel 54 at 6:00 am on the given weekday. Inthis instance, the statistics captured in table 1000 are based on a timegranularity of 10 minutes. As a result, the next entry, i.e., entry1023, in column 1011 corresponds to 6:10 am at which 50 set-topterminals in the given service area are tuned to program channel 54.Column 1011 in this instance also shows that at 6:20 am, 51 set-topterminals in the given service area are tuned to program channel 54; at6:30 am, 66 set-top terminals in the given service area are tuned to thesame program channel; . . . and so on and so forth. The viewership of aprogram channel may be considered to be strong when the number ofset-top terminals in a service area tuned to the program channel exceedsa predetermined threshold, e.g., 10 in this instance. The actual valueof the threshold may vary with the total number of set-top terminals ina service area. In this instance the viewership of program channel 54, amusic video channel, is strong throughout the day, with the exception ofa few brief intervals (e.g., interval 1033), perhaps because the musicvideos played during those intervals are unentertaining.

In this example, because of the generally strong viewership of programchannel 54, processor 804 determines that program channel 54 is apopular program channel at least for the given weekday. Processor 804further analyzes and cross-references other daily statistics to obtain apattern of viewership of program channel 54. If, for example, processor804 determines that program channel 54 is popular each day, processor804 may assign a carrier, on a permanent basis, to deliver programmingcontent of program channel 54 to the given service area, in accordancewith the invention. Similarly, if processor 804 determines that programchannel 54 is only popular on a particular weekday each week, processor804 may assign a carrier, on a weekly basis, to deliver its programmingcontent to the given service area on that particular weekday, and forthe other days of the week, program channel 54 is subject is switchedbroadcast.

Based on the viewing statistics in table 1000, processor 804 alsodetermines viewing habits of the subscribers in the given service area.For example, based on the statistics in column 1003, processor 804determines that the viewership of program channel 50, a talk showchannel, is relatively strong in the daytime (e.g., 6:00 am through 6:30pm) but relatively weak in the nighttime (e.g., 6:30 pm through 2:00am). On the other hand, based on the statistics in column 1005,processor 804 determines that the viewership of program channel 51, amovie channel, is relatively weak in the daytime but relatively strongin the nighttime. As a result, program channel 50 and program channel 51seem to be complementary, where channel 50 is popular while channel 51becomes unpopular, and vice versa, at least for the given weekday.Processor 804 further analyzes and cross-references other dailystatistics to obtain a viewership pattern for both program channels 50and 51. If, for example, processor 804 determines that program channel50 is popular during the daytime of each weekday, and program channel 51is popular during the nighttime of each weekday, processor 804 mayassign a specific carrier to alternately deliver channel 50 daytimeprogramming content and channel 51 nighttime programming content to thegiven service area each weekday, according to the viewing habit of thesubscribers in that service area. That is, program channel 50 (51) inthis instance is assigned the specific carrier during the daytime(nighttime) of each weekday and is subject to switched broadcast for therest of the time.

Other subscriber viewing habits may be uncovered by processor 804analyzing weekday viewing statistics, e.g., table 1000, and weekendviewing statistics (not shown) aggregately. For example, processor 804in this instance determines that although program channel 52, a cartoonchannel, and program channel 53, a sports channel, are generallyunpopular on weekdays, they are popular in certain periods on weekends.Specifically, the viewership of program channel 52 is particularlystrong on weekend mornings while the viewership of program channel 53 isparticularly strong on weekend afternoons. As such, processor 804 inthis instance assigns a specific carrier to deliver channel 52 (53)programming content to the given service area during weekend mornings(afternoons), and for the rest of the time, channel 52 (53) is subjectto switched broadcast. In addition, processor 804 in this instancedetermines that movie channel 51 is popular during weekend nights aswell. As such, the same carrier may be assigned to deliver channel 51programming content to the given service area during weekend nights.Indeed, in this instance the same carrier may be cycled through programchannels 50, 51, 52 and 53 each week, which are complementary.

It should be noted that viewing statistics may be captured on a dailybasis, e.g., table 1000. They may otherwise be captured on a larger orsmaller scale to identify subscriber viewing habits in a time frame ofparticular interest. For example, by capturing viewing statistics on amonthly basis, processor 804 may identify any monthly or seasonalviewing habits with respect to a particular program channel. If, forexample, based on the monthly statistics processor 804 determines thatprogram channel 54 is generally popular for only one of the fourseasons, say summer. Accordingly, processor 804 may assign a specificcarrier to deliver channel 54 programming content to the given servicearea for summers only, and for other seasons, channel 54 is subject toswitched broadcast.

In another embodiment, based on the viewing statistics such as thosecaptured in table 1000, processor 804 also determines what programs,program lineups or even program channels are unpopular and not wellreceived by the audience. For example, by correlating the start and endtimes of interval 1033 with a broadcast program schedule, processor 804may identify those unentertaining music videos played during interval1033. Processor 804 may further analyze and cross-reference otherviewing statistics to determine any viewership pattern regarding suchmusic videos in terms of time and geographic region. For example, (I) bycross-referencing other daily statistics associated with the servicearea, processor 804 may determine that the music videos in question areunpopular all the time or only during certain time of day, day of week,etc. in the service area; (II) by cross-referencing other dailystatistics associated with other service areas, processor 804 maydetermine that the music videos in question may also be unpopular, atcertain times or all the time, in other service areas comprising aregion, e.g., the South, Midwest, Northeast, West Coast, etc. or thewhole country. Thus, by similarly performing (I) and/or (II) on viewingstatistics to determine popularity or unpopularity of a program, programlineup or even a program channel, processor 804 may furnish serviceproviders, advertisement sales and research groups with valuabledemographics concerning such a program, program lineup or programchannel. Of course, (I) and (II) may be similarly performed to identifypopular programs, program lineups or program channels, which are subjectto renewal due to strong viewership. The same applies to commercials andelements of TV shows, e.g., skits, monologues, chapters, etc., made partof TV shows. For example, by adjusting the time granularity of viewingstatistics from 10 minutes as in table 1000 to, say, 30 seconds (thelength of a typical commercial) or less, processor 804 may determinebased on the viewing statistics the popularity or unpopularity of agiven commercial in terms of time and/or geographic regions. Such databy processor 804 is conducive to providing demographically targetedcommercials.

The foregoing merely illustrates the principles of the invention. Itwill thus be appreciated that those skilled in the art will be able todevise numerous other arrangements which embody the principles of theinvention and are thus within its spirit and scope.

For example, in the disclosed embodiment, modulator bank 106, combiner108, optical transceiver 110 and demodulator 130 are illustrativelyco-located in headend 100. However, one or more of these components maybe located outside headend 100.

In addition, system 10 is disclosed herein in a form in which variousfunctions are performed by discrete functional blocks. However, any oneor more of these functions could equally well be embodied in anarrangement in which the functions of any one or more of those blocks orindeed, all of the functions thereof, are realized, for example, by oneor more appropriately programmed processors such as digital signalprocessors (DSPs). Thus, for example, switching unit 104 and modulatorbank 106 in system 10 may be realized by one or more DSPs. A DSPtypically comprises a combination of digital logic devices and othercomponents, which may be a state machine or implemented with a dedicatedmicroprocessor or micro-controller running a software program or havingfunctions programmed in firmware.

What is claimed is: 1-66. (canceled)
 67. Apparatus configured tocontrollably deliver programming content associated with a programsource in response to requests from a plurality of terminals in aservice area, said apparatus comprising: an interface configured toreceive said requests; a memory configured to store a first set ofstatistics generated based on data obtained from first ones of saidrequests received during a first time interval; and a processing elementconfigured to: identify, based on said first set of statistics, thatsaid program source has previously attained a threshold level of demandin said service area at an identified period of time within said firsttime interval; based on said identification, assign a selected carrierto deliver said programming content associated with said program sourceto said service area during said identified period of time, said carriernot reassigned to a different program source when there are no userrequests for said programming content nor users currently tuned to saidprogramming content; and deliver said programming content associatedwith said program source to said service area according to switcheddigital broadcast mechanisms at times other than said identified periodof time.
 68. The apparatus of claim 67, wherein said program sourceincludes a program channel.
 69. The apparatus of claim 67, wherein saidthreshold level of demand varies with a total number of terminals insaid service area.
 70. The apparatus of claim 67, wherein at least oneof said requests for said programming content comprises a request toprovide programming content associated with said program source.
 71. Theapparatus of claim 67, wherein said processing element is furtherconfigured to reassign a second carrier to said different program sourcefrom a second program source when there are no user requests for asecond programming content associated with said second program sourcenor users currently tuned to said second program source when said secondprogram source has not previously attained said threshold level ofdemand in said service area.
 72. The apparatus of claim 71, wherein saidprocessing element is further configured to update a channel assignmenttable stored in said memory based on said reassignment of said secondcarrier to said different program, said channel assignment table mappingeach program source selectable by a subscriber, a carrier assignment ofsaid each program source and a number of currently tuned subscribers ofsaid each program source.
 73. The apparatus of claim 67, wherein saidprocessing element is further configured to determine that there are nousers currently tuned to said program source via a look up to a channelassignment table stored in said memory, said channel assignment tablemapping each program source selectable by a subscriber and a number ofcurrently tuned subscribers.
 74. A method for controllably delivering afirst programming content associated with a first program source andsecond programming content associated with a second program source inresponse to requests from a plurality of terminals in a service area,said method comprising: storing a set of statistics based on dataobtained from requests received for program content, said requestscomprising requests for said first programming content from said firstprogram source and requests for said second programming content fromsaid second program source received during a first time interval;identifying, based at least in part on said set of statistics, a firstplurality of future time periods in which said first program source willattain a threshold level of demand in said service area and acomplementary plurality of future time periods in which said secondprogram source will attain said threshold level of demand in saidservice area, said first plurality of future time periods and saidcomplementary plurality of future time periods being mutually exclusivetime periods; assigning, based on said identification, a selectedcarrier to deliver said first programming content associated with saidfirst program source to said service area during said first plurality offuture time periods; during periods other than said first plurality offuture time periods, causing said first programming content associatedwith said first program source to be delivered to said service areaaccording to switched digital broadcast mechanisms; assigning, based onsaid identification, said selected carrier to deliver said secondprogramming content associated with said second program source to saidservice area during said complementary plurality of future time periods;and during periods other than said complementary plurality of futuretime periods, causing said second programming content associated withsaid second program source to be delivered to said service areaaccording to switched digital broadcast mechanisms.
 75. The method ofclaim 74, wherein said first and second program source each comprises aparticular one of a plurality of program channels.
 76. The method ofclaim 74, wherein said threshold level of demand varies based at leastin part on a total number of terminals in said service area.
 77. Themethod of claim 74, wherein said set of statistics are based on channelrequest data.
 78. The method of claim 77, wherein said channel requestdata comprises a request to provide programming content associated withsaid first program source.
 79. The method of claim 77, wherein saidchannel request data comprises a request to stop delivery of programmingcontent.
 80. The method of claim 74, further comprising analyzing saidset of statistics by cross referencing said set of statistics with otherdaily statistics to obtain a pattern of viewership for at least saidfirst content source and said second content source.
 81. Anon-transitory computer readable apparatus comprising a plurality ofinstructions which are configured to, when executed by a processorcontrollably deliver programming content associated with a programsource in response to requests from a plurality of terminals in aservice area via: collection of tuning data comprising a plurality ofrecords associated with a plurality of program channels in a switcheddigital network, each of said plurality of records comprising atimestamp of a channel change request, a channel identifier associatedwith a first programming channel, and a service area identifier of aparticular service area; based on said collection of said plurality ofrecords, determination of a number of subscribers in said particularservice area which are currently tuned to said first programmingchannel; generation of a set of service area specific statistics basedon said collection of said tuning data, said set of service areaspecific statistics comprising viewership at different time intervals;identification, based at least in part on said set of service areaspecific statistics, of a plurality of time periods in which saidprogram source is predicted to attain at least a threshold level ofdemand; assignment of a selected carrier to deliver said programmingcontent associated with said program source to said service area duringsaid identified periods based at least in part on said set of servicearea specific statistics, said carrier not being reassigned to adifferent program source when there is a lack of user requests for saidprogramming content existing during said identified periods; and duringperiods other than said identified future periods, delivery of saidprogramming content associated with said program source to said servicearea according to switched digital broadcast mechanisms.
 82. Theapparatus of claim 81, wherein said number of subscribers in saidservice area which are currently tuned to said first programming channelis based on a value in an assignment table of said service area, saidassignment table mapping a set of program channels with said number ofsubscribers in said service area tuned to said first programming channeland an assigned carrier of said first programming channel.
 83. Theapparatus of claim 81, wherein said plurality of instructions arefurther configured to, when executed by said processor generategeographic region based statistics to determine viewership trends on aregional basis.
 84. The apparatus of claim 81, wherein the programsource comprises a particular one of a plurality of program channels.85. The apparatus of claim 81, wherein the threshold varies based atleast in part on a total number of terminals in the service area. 86.The apparatus of claim 81, wherein said plurality of instructions arefurther configured to, when executed by said processor correlate saidset of service area specific statistics with a broadcast programschedule to determine viewership patterns of particular programmingcontent.